I lived islington for several years and worked there for even longer. Upper Street is one of the best places you will ever visit.
This was our fave pub, one of the best in the city
https://www.the-albion.co.uk/ but the Victoria Tavern was right next door so we usually went there.
Our offices were in a converted baroque church at the junction of Liverpool road and Holloway, it was handy because it was a short walk to either Caledonian Road, Holloway Road or Highbury and islington tube stations depending what line you wanted to be on. Plus, the boss was a big Arsenal fan and it was short walk to the stadium for mid week matches.
I worked as a field engineer for a company supporting publishing, music and video systems, I have been to and worked in all of the locations on your map.
Never a problem in any of them. I still travel down to do jobs around the city, I speak from first hand experience. You are full of crap.
My sister lived in Elephant and Castle for years
Camden is famous for being a hip, trendy tourist destination.
As for Kentish town
11-reasons-why-its-the-best-place-to-live-in-london